There have been being widely used disc recording media as a transportable information recording medium used in a computer system or an image/audio recorder/reproducer, the disc recording medium typically being a CD (compact disc) and a DVD (digital versatile disc).
Although there is known a disc recording medium that is loaded in the recorder/reproducer in a state in which the medium is housed in a case or caddy, a disc recording medium that is loaded with its disc body exposed is widely used.
As a recorder/reproducer (or a computer system) in which the exposed disc recording medium is loaded, a slot-in type recorder/reproducer will be described.
The slot-in type recorder/reproducer employs a transport mechanism that includes an injection/ejection slot through which a disc can be passed, a roller that contacts with the disc inserted from the insertion/ejection slot, a transport motor that rotates the roller and the like. In order to load the disc, when a circumferential end of the disc recording medium is inserted into the insertion/ejection slot, the roller contacts with a back surface of the disc recording medium and the roller is rotated by the transport motor, whereby the disc recording medium is transported to a predetermined position in Related Art 1 or the disc recording medium is sandwiched by a pair of the rollers from its diametrical sides to be transported in Related Art 2 (see Patent Document 1).
In Related Art 1, a surface of the rollers is coated with a rubber material, and the roller is tapered such that the diameter thereof is small at a middle portion and increases toward both end portions. With the arrangement, although the roller contacts with the disc recording medium from a recording surface side, the roller mainly contacts with the circumferential end portion of the recording surface so that an influence on the recording surface can be minimized.
Provided on a side opposite to the roller is a guide member for maintaining the disc recoding medium on a transport path. The guide member is formed in a rib shape extending in a direction intersecting with a transport direction of the disc recording medium in order to meet a front-width variation depending on its insertion depth of the disc recoding medium or to meet a later-described difference in diameters of disc recoding media. The rib-like guide member is so formed as to contact with the circumferential end portion of the disc recoding medium in order to prevent or reduce an influence (e.g., wear) on the surface of the disc recording medium.
With the arrangement, the rib-like guide member has a predetermined inclination such that the height of the guide member is large (a projection amount is large) at both end sides of the slot and small at a middle portion of the slot, namely the height increases toward the both end sides.
In such a related art slot-in type recorder/reproducer, the transport mechanism needs to be actuated when a portion of the disc recording medium is inserted from the slot. For this purpose, a disc recording medium transport device is provided with a contact-type detection mechanism that is arranged on an inner side of the slot. In addition, there are two diameter types (12 cm and 8 cm) in CDs or the like, and the difference in diameters is also detected by the detection mechanism.
The detection mechanism includes a guide rail provided along the inner side of the slot, a moving member provided so as to be movable along the guide rail, a contact member (e.g., a projection) that is provided on the moving member and contacts with the circumferential end of the disc and a plurality of switches that is disposed on predetermined positions along the guide rail to detect passage of the moving member.
Typically, the moving member provided with the contact member and the guide rail are arranged as a unit and a pair of the units is disposed on both sides of the slot. By disposing the pair of units, even when the center of the inserted disc recording medium is slightly displaced, the front width of the inserted disc can be accurately detected as a distance between the contact members on both sides.
In the contact-type detection mechanism, when the disc recording medium is inserted into the slot by a predetermined depth, the contact members are pushed outward by the circumference end of the disc to reach the predetermined front width that causes the transport motor to be actuated.
One of the switches is disposed at a position where it is disconnected when the predetermined front width causing the transport motor to be actuated is exceeded, and this switch disconnection actuates the transport motor associated with the insertion of the disc recording medium.
The guide rails each have a sufficient width extending to reach an end of the slot, which allows the contact members to move along the guide rails together with the moving members and to be opened wider than the diameter of the transported disc, so that the passage of the disc is not impeded.
Another ones of the switches are so set as to be each disconnected when the maximum width (diameter) of the passing disc recording medium is 12 cm or 8 cm, thereby detecting the diameter of the inserted disc.
Related Art 2 disclosed in Patent Document 1 includes a pair of roller mechanisms disposed near the both ends of the slot for sandwiching the disc recording medium from the diametrical sides thereof, the roller mechanisms each including rollers adapted to move toward or apart from each other. In order to transport the disc recording medium to a predetermined position in the device, each of the roller mechanisms includes two pairs of the rollers that are provided along the transport direction.
[Patent Document 1] JP-A-2002-304798 (FIG. 1)